Both carbonated and non-carbonated beverages may be stored in a frozen or partially frozen state and dispensed in the form of a slush. Typically, frozen or partially frozen beverages are stored and dispensed under pressure.
One problem associated with prior art apparatus for dispensing frozen beverages is that refrigerant is typically stored under relatively high pressure (e.g., 37 psi) in a storage tank or the like. A dispensing valve is connected to the storage tank and is operable by means of a lever or other manually operable device. When the valve is open, there is often a sudden blast of the pressurized beverage, which cannot only result in an unpleasant surprise to the person operating the dispensing valve, but can also result in loss of control of the cup or other container used to capture the beverage by the person operating the dispensing valve. The problem is exacerbated when the dispensing apparatus is in a defrost cycle. During the defrost cycle the beverage may be at least partially melted. If the dispensing valve is operated during the defrost cycle, the beverage will be dispensed at an even greater force because it is in a more liquid state.
Another problem associated with prior art dispensing apparatus is the problem or residual leakage after the dispensing apparatus has been operated. Typically, some of the beverage will be present in the dispensing valve body downstream of the valve seat. Even after the dispensing valve has been closed, this residual material may leak from the dispensing faucet connected to the valve body.
U.S. Pat. No. 4,911,333 discloses a beverage dispensing valve having a valve seat with a specially designed passageway that directs the frozen material radially outward toward the walls of the valve bore rather than axially toward the valve outlet. A manually operable lever is used to move a valve pin into and out of engagement with the valve seat to close and open the valve, respectively. A lockout mender engages an opening in the valve pin to prevent the valve pin from being moved to the open position when the dispensing apparatus is in a defrost cycle. The lockout member engages the valve pin inside the valve body.
Although the valve seat disclosed in U.S. Pat. No. 4,911,333 reduces the dispensing pressure, the dispensing valve is still subject to leakage after the valve is closed because of the frozen material inside the passageway of the valve seat and in the faucet portion beneath the valve seat, particularly after the frozen material has melted. Another problem associated with the dispensing apparatus of U.S. Pat. No. 4,911,333 is that the lockout member engages the valve pin inside the valve body, such that the lockout condition is not apparent to one who may attempt to operate the valve, such as a member of the general public. Forceful operation of the lever may disengage the lockout member from the valve pin or even break the lockout member.
There is therefore a need for improved frozen beverage dispensing apparatus to overcome the aforementioned problems of dispensing pressure and leakage.